Theory of Operation
The ISM Engine Protection feature is always on duty. The ECM is constantly watching parameters to ensure that the engine is operating within safe limits. The electronic control system will alert the operator and automatically de-rate the engine speed and/or power if the operation of the engine is deemed "out of range". There is also the customer option of actual engine shutdown that can protect your engine from progressive damage. Additionally, the customer has the option to prevent engine restart after 5 consecutive shutdowns.
How it Works
The electronic control system monitors engine speed, oil pressure, coolant temperature, coolant level, fuel temperature, and intake manifold temperature for normal operating conditions. If the limits of normal operation are exceeded, the engine will trigger the red (stop), yellow (warning), or blue (maintenance) lamps, perform the appropriate speed or power de-rate, and log the appropriate fault code.
All engine protection modes have a corresponding fault code that will log the same as other diagnostic fault codes. These fault codes should be diagnosed with the same procedures as other fault codes that occur during engine operation. The lamp and de-rate are chosen according to the severity of the out-of-range parameter.
If the shutdown option is enabled, the shutdown timer starts as soon an engine parameter exceeds the limits of normal operation. The red (stop) lamp also begins flashing. If the out-of-range parameter returns to the limits of operation, the engine will return to normal and bypass the shutdown sequence. After a complete 30 second shutdown sequence, the timer will shut the engine down. At this point the engine can be restarted by cycling the key switch. The red (stop) lamp will continue flashing and the engine will be limited by the maximum speed/power de-rate associated with the out-of-range parameter.
The Engine Protection Feature keeps a log of which engine parameters were exceeded, how many times, how long, and the maximum out-of-range parameter. This data is compiled in the Engine Protection reports and is very useful in the engine diagnostic process. (See below for reporting details).
If the vehicle is equipped with an optional Cummins RoadRelay , the operator will also have immediate access to the fault code, fault description and required operator response.
Protection at Start Up
Engine Protection is always active while the engine is running. At engine startup, the speed of the engine will be limited until a safe oil pressure is achieved.
Cummins INSITE must be used to access the data compiled by the Engine Protection feature. The reports provide summary and detailed information on which parameters have exceeded the safe operating range. This data can be very useful in the engine diagnostic process.
The Engine Protection Data Report is a summary of the engine protection modes with the corresponding fault code, maximum parameter value, length of time active, and time of last occurrence. It is best to use this report for a general summary of all Engine Protection activity.
The Engine Protection Fault History Report displays a separate summary for each engine protection mode. All occurrences of the specific mode are ul>
Neither of the reports can be reset. Information gathered by the Engine Protection feature is kept for the life of the engine. The corresponding fault code that is logged when the engine exceeds the limits of safe operation should be diagnosed using the same procedures as other fault codes that occur during engine operation.
Keys to Success
The Engine Protection feature relies on the operator's ability to recognize the lamp sequences. Training operators on how the feature works and what to expect is essential.
If the vehicle is equipped with an optional Cummins RoadRelay , the fault code, a fault description and the required operator response, will be immediately displayed.